Polyglycerol resin



( UNITED s'ra'ras PATENT oFrlcE.

LOUIS wnrsisnae am) aanrii s. ror'rna, orem'rwoon; NEW masrmassrexons TOTHE BARRETT comramr, A coaroaa'rron or NEW mnsmr.

A roLYeLYcEaor. RESIN.

Io Drawing.

lowing is a specification.

This invention relates to new and useful improvements in s ntheticresinous products and in processes or making the same. It has been knownfor sometime that resinous bodies could be formed b heating together apolyhydric alcohol, a po ybasio acid of the aromatic series, and adibasic acid of the ali-. phatic series. Most of these resins containgllyq cerol and phthalic anhydride and one ot er acid such as succinic,malic, tartaric, maleic, or fumaric acid. According to the amount of thealiphatic acid used, products of widely different physical propertiesare obtained." Thus, without any aliphatic acid at all, the product isextremely brittle, while if the proportion of aliphatic acid issufiiciently increased, a tough, elastic body is produced. By propertreatment these resins may be rendered substantially inert to water andmany ordinary chemicals, thus making them useful in a variety ofapplications where resistance to water is required.

Three 'classes of resins may be distinguished, namely:

Glass A.-Initial condensation product; soluble in acetone; fusiblemelting point seldom exceeds 120 C. (temperatures throughout thisspecification are on the centigrade scale) not resistant to cold water;passes on further heating into a resin of class B.

Class B.Intermediate condensation product; insoluble in acetone;infusible; can be molded under heat and pressure; not resistant to coldwater; passes on suitable heat treatment into a resin of class C.

Class U. Final condensation product; in soluble in acetone; infusible;can be molded under heat and pressure; resistant to both hot and coldwater.

These difierent products may be made from the same starting materials bysuitably 'modifying the temperature and duration of heating. The initiacondensation roduct is an A-resin, the intermediate pro ueta B- resin,and the'final condensation product a C-resin. The greater the extent towhich the substances called polyglycerols.

Specification of Letters Patent. Pat t d July 25, Application me aFebruary 19, 1921; Serial 1%. 440,509.

heat treatment is carried, the more inert is This time is particularlylong in that process of manufacture, wherein the'production of abubble-free product depends on carrying out the reaction ata temperaturebelow the melting point of the resin. At such temperature the reactionproceeds so slowly that the time required to produce the finishedproduct constitutes a serious obstacle Bythe present invention a markedsaving in time (hence, in expense of manufacture) is effected.

This saving of time is especially important in the production of moldedarticles when, as is often desired, the final heat treatment is carriedout within the mold itself. Each mold is thereby enabled to turn out agreater number of pieces in a workin day or in a given time, and sincesuch mol s are often expensive, the cost of each piece is correspondin1y lowered.

It is we 1 known that polyhydric alcohols are generally capable ofbeing'condensed with themselves to iform more complex bodies. Thiscondensation is nerally regarded as taking place with e imination of.

\ alcohols.

For example, when glycerol (which is a polyhydric alcohol) is distilled,the residue in the'still consists largely of a. mixture' of These aremainly diand triglyoerols, and are said to be formed by elimination ofwater between two or moremolecules of glycerol. There are a number ofmethods by which a better yield of polyglycerols ma be obtained; forexample, b the ad ''tion of about one-half per cent 0 sodium hydroxideor of sodium acetate and heating for a half hour near 280 C., thegreater part of the glycerol may be converted to a mixture of V as forexample diand triglycerols. This mixture is a liquid which is moreviscous than glycerol itself, and from which the various constituentscan be separated by distillation under diminished pressure. Thisseparation, however, is not necessary, as the unseparated mixture servesvery well as a starting point for making resins.

It is to be understood that any suitable method for making thesepolyglycerols may be employed; for the present invention relates to theutilization of polyglycerols, of whatever origin or however made orproduced, in the manufacture of resins and not to the manufacture of thepolyglycerols themselves. It is to be understood also that othercondensed polyhydric alcohols, as well as the poly lycerols, may beemployed,

, file polyglycols.

To make resins from polyglycerols, the procedure is similar to that whenglycerol itself is used, except that certain precautions must beobserved on account of the greater speed with which the reaction takesplace, especially in making the class A- resin. At 170 C. for instance,the polyglycerols produce class A-resin -more than five times as rapidlyas glycerol. It is important at the start to raise the temperatureslowly until the acids are completely dissolved. Otherwise the reactionmay proceed too quickly to a point where the resin isno longer fusible,and some of the acid may be left undissolved. The rate at which thetemperature may be raised depends primarily on the acids used. Phthalican hydride, maleic acid, and malic acid dissolve much more readily, forexample, than does fumaric acid.

In practicing this invention the polyglycerols may be heated with adibasic aromatic acid. A polybasic aliphatic acid may be substitutedwholly or in part for the aromatic acid, and as soon as the mixturebecomes homogeneous, the temperature may be raised more rapidly. Thecolor of the mixture is dependent upon "the purity of the constituents.The mixture is of a clear yellow color if the constituents aresufiiciently pure. At first the mixture is soft and sticky, but as theheating 0ontinues, the meltin point rises, and the stickiness eventuallyisappears. If the heating is interrupted when this stage is reached, theproduct has the properties of a resin of class A.

The A-resin, on further heating, passes into a resin of class B. Whenthis heating is carried out at a temperature below the melting point ofthe A-resin, a homogeneous bubble-free product is obtained inapproximately one-half the time required when lycerol is used. At highertemperatures 510 reaction becomes violent, heat is evolved, and theproduct becomes filled with bubbles use of polyglycerols with and isfrothy. This frothy product ma be ground and molded under pressure. hisremoves the bubbles; so in the end a good B-stage product may beobtained by elther method of heating.

After the B-sta is reached, the resin may be heated to a ighertemperature without danger of frothlng, provided that the temperature isnot raised too suddenly. The larger the mass of material being handled,the greater is the care required in this regard. When the B-resin isheated at a temperature of 170 or higher, a further transformation takeslace. This results in the production of the -resin. This reaction isusually carried out at the highest practicable temperature in order tosave time. The temperature is nearly always as high as 200 and may evenreach 250. The reaction may be completed in a shorter time with thepolyglycerol resins than with the ordinary glycerol resins. It has beenfound in many cases that not more than half the time is required. It isfrequently desirable to carry out this finishing heat treatment withinthe mold, and wherever this is the case the polyglycerol resins are,therefore, to be preferred to the glycerol resins.

The physical propertles of the so obtained polyglycerol resins do notdiffer greatly from the corresponding glycerol resins. Accordingly, theycan be employed generally in place of the glycerol resins and withequally satisfactory results. In one case, however, there is a notableimprovement. Resins made from glycerol and phthalic anhydride are sobrittle and sensitive to shock that for many technical purposes it hasbeen necessary to replace part of the phthalic anh dride by certainpolybasic aliphatic aci which are at present more expensive thanphthalic anhydride, such as succinic, malic, tartaric, maleic, fumaric,citric. or malomalic acid, thus producing tougher and more elasticresins. To a considerable degree, the same effect may be obtained simplyby the hthallc anhydride in place of glycerol. bus the work reqluired tobreak a polyglycerol-phthalic an ydride test specimen is approximatelytwice that required for a similar ,gl cerolphthalic anhydride resin(measured on a.

all impact machine). The main improvement by the polyglycerol process,however, is the saving 1n time and expense of manufacture; the pointjust mentioned is, however, of considerable importance and is a furtheradvantage which may be obtained by the ractice of this invention.

T e advantage of the poly lycerol process extends through all stages 0the condensasation and so applies to the manufacture of all the classesof resins enumerated. Among the acids which may be emplo ed in thisprocess are phthalic acid or pht alic anhydride. Either the acidsthemselves or the anh drides of other polynuclear aromatic aci s, suchas diphenic acid, 1.8 naphthalic acid, benzoyl-benzoic acid,chlor-benzoylbenzoic acid, and methyl-benzoyl-benzoic acid, may besubstituted in part or wholly for phthalic acid oranhydride with goodresults. Also, polybasic aliphatic acids, such as succinic, malic,tartaric, maleic, fumaric, citric, or malo-malic acids may be used.Mixtures of these acids may also be employed to produce the resins, butit is preferable to have always present at least a small percentage ofan aromatic acid for the best results. The term polyglycerol is used inthe claims in a broad sense and is meant to include the polyglycols andsimilar condensed polyhydric alcohols.

These resins, on heating with a twenty percent solution of caustic soda,produce a result from which a polyhydric alcohol and the acid or acidsemployed, or the transformation product of the acid or acids employedmay be recovered by means well understood by chemists. .For example,maleic acid may be recovered entirely or in part as fumaric acid. Morespecifically, a specimen may be boiled with about ten times its bulk ofa twenty percent solution of caustic soda filtered, cooled and acidifiedwith hydrochloric acid. From the product of these operations the alcoholand the acid or acids employed in making the resin may be recovered.

The polyglycerol resins ma be mixed with shellac as disclosed in U. iPatent No. 1,413,144, and the mixtures used as a varnish or moldingcomposition to replace shellac.

They may also be used for such purposes as storage battery tanks,phonograph records,

molded insulation, and molded articles generally, due regard in eachcase being paid to the choice of resin according to the requirements forthe purpose intended.

e claim:

1. The process which comprises heating a polyglycerol and a polybasicacid of the aromatic series until a water-resistant product results.

2. The process which comprises heating a polyglycerol, a polybasic acidof the aromatic series and a polybasic acid of the aliphatic seriesuntil a water-resistant product results.

3. The process which comprises heating a polyglycerol, and a, dibasicacid of the aro matic series and a polybasic acid of the aliphaticseries until a water-resistant product results.

4. The process which comprises heating a'polyglycerol and a polybasicacid of the aromatic series until an infusible and a water-resistantproduct results.

tures.

LOUIS WEISBERG. RALPH S. POTTER.

